The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The use of electric drive units (“EDUs”) in passenger vehicles is gaining rapidly in popularity, owing in part to the increasing interest in reducing the carbon footprint associated with typical four wheeled passenger vehicles, which traditionally have used internal combustion engines for power. In previously developed EDUs, either an induction motor or a permanent magnet (“PM”) motor have most typically been used when either supplementing, or supplanting, an internal combustion engine of a vehicle. Induction motors generally provide maximum efficiency at moderate to high rotational speeds and lower output shaft torques. Conversely, a PM motor differs in that its peak efficiency generally occurs at lower to moderate motor shaft speeds, and over a wider output torque range, than an induction motor. FIGS. 1 and 2 provide graphs illustrating how the efficiency of each of a PM motor and an induction motor change with speed and output torque.
With the present day interest in maximizing efficiency and obtaining the maximum driving range of vehicles having an EDU, there is strong focus on developing EDUs that even better meet the needs of maximizing efficiency while providing maximum efficiency over a wider speed range, as well as over a wider output torque range.